Several knife holders attached to a cutter bar are used for cutting sheet material lengthwise. The individual knife holders essentially comprise one controllable lowering device, on which a circular cutting knife is positioned on a cutter head, such that it can rotate. The individual knife holders are mounted detachably on the cutter bar, so that the desired cutting widths can be adjusted by adjusting the mutual distances between neighboring knife holders. The circular cutting knives wear out over time and must therefore be replaced from time to time to maintain the cutting quality. The circular cutting knife, which is attached with the aid of a ring nut to the cutter head, can be pulled off the cutter head once the ring nut is unscrewed and can be replaced with a new circular cutting knife. However, these operations are time consuming and, in particular, are difficult to carry out when cutting narrow material sheets. With extremely narrow cutting widths, the required access to the ring nut does not even exist, so that the knife holder must be removed altogether.
It is the object of the invention to create a device for cutting material sheets of the aforementioned type in lengthwise direction, which device permits an easy replacement of damaged or worn circular cutting knives.
This object is solved according to the invention with a device for cutting material sheets lengthwise, which device contains a knife holder that can be attached to a cutter bar. The knife holder essentially consists of a support body and a cutter head that is provided with a circular cutting knife. The cutter head is adjustable in vertical and horizontal direction, relative to the support body, and is provided with an interlocking, plug-type connector for connecting the support body to the cutter head and/or the cutter bar. The plug-in direction of this connector extends in the plane for the circular cutting knife.
With a knife holder designed in this way, it is possible to replace a damaged or worn circular cutting knife without having to remove the knife holder from the cutter bar, even if the individual knife holders are arranged tightly adjoining on the cutter bar. The specified position of the knife holder, relative to the adjacent knife holders, is thus maintained. Following the release of the interlocking, the cutter head as a whole can be pulled off the support body toward the front. In place of the cutter head with the damaged circular cutting knife, a cutter head with a new circular cutting knife is then fitted onto the support body and is interlocked with this body, so that the full function is restored once more.
The solution according to the invention can also be used with a device for cutting material sheets lengthwise, for which the knife holders are not connected directly to the cutter bar, but to an adapter slide that can be moved along the cutter bar and can be locked in place thereon. With a device of this type, a corresponding plug-type connector between support body and adapter slide can be provided in addition to or in place of the plug-type connector between cutter head and support body. Given a system of this type and following the release of the interlocked plug-in connection, the complete knife holder is lifted in upward direction off the adapter slide and is replaced by a new knife holder. This occurs without a change in the positioning, relative to the neighboring knife holders, which is predetermined by the positioning of the adapter slide. A measure of this type is required, in particular, if the standard pneumatic adjustment device in the support body for the vertical movement of the cutter head no longer operates without problems or is not operational at all, for example as a result of leaks in the piston-cylinder system.
One preferred embodiment of the invention provides that the plug-type connector is formed by a guide pin on the one part and a corresponding receptacle for the guide pin on the other part, as well as the coordinated form-fitting surfaces on both parts. The preferably cylindrical guide pin can be bought cheaply as prefabricated, semi-finished product. Accordingly, the hole for the guide pin is simply a corresponding mating bore. As a result of this arrangement of the coordinated form-fitting surfaces, which function to tension the two parts against each other via the interlocking, it is ensured that the two parts are rigidly connected and that the breakdown torque as well as the torque, introduced by the cutting forces, are reliably absorbed.
One advantageous embodiment of the invention furthermore provides that the interlocking connection is formed by a screw tensioning the guide pin against the hole. An interlocking connection of this type is easy to produce since the guide pin is provided with an axial thread bore. In addition, it has the advantage that the interlocking is also accessible in plug-in direction. In that case, the screw can be designed, for example, as hexagon socket screw, so that it is easy to create the interlocking connection by using an appropriate screwdriver.
According to one preferred embodiment of the invention, the coordinated formlocking surfaces are formed by a cross bolt on the guide pin and a recess in the receiving mating bore.
Another embodiment of the invention provides that the form-locking surfaces are formed by coordinated wedge-shaped surfaces that face each other. This embodiment has the advantage of providing relatively large, contacting surface areas, so that the permissible surface pressures are not exceeded, even for high pressing forces. Another advantage of this embodiment having wedge-shaped surfaces is that there is no play in plug-type connector because the surfaces are tensioned against each other. The embodiment can also be used in conjunction with the previously described cross bolts.